Tiny computers could transform our lives

Remember Innerspace,
the comedy sci-fi movie from the ‘80s about a microscopic manned pod injected
into a human? Although we’re years away from launching submarines inside our
bodies, advances in engineering have made it possible to build computers so
tiny that embedding them inside living tissue is no longer a figment of a
sci-fi writer’s imagination. Indeed, it’s now been 20 years since British
scientist Kevin Warwick first implanted a silicon
RFID transmitter into his arm to remotely control computers in
doors, lights and other devices. He then took it a step further by interfacing
the device with his
own nervous system to control a robotic arm, earning
himself the nickname “Captain Cyborg.”

While it’s
not headline news every day, the pace of microcomputer technology has not
slowed, and I’m still occasionally astounded by the ingenuity of some new
developments.

For example, earlier this year, a team at the University of Michigan led by professor of electrical and computer engineering David Blaauw used an energy-efficient processor built by Arm to construct the world’s smallest computer.

Measuring
just 0.3
mm to a side, the device is just one tenth the size of the previous
record holder, a solar-powered computer no larger than a grain of
salt. Because temperature and pressure sensors can be built into the new
device, Blaauw’s team envisions that, among other applications, it could be
implanted into tumors to determine whether they shrink after chemotherapy
treatments. (Studies show that tumors may have slightly
higher temperatures than healthy tissue.)

Although the development of tiny computers is exciting, there are obstacles preventing them from being deployed widely in healthcare and other sectors. One of the biggest problems is building batteries small enough to power the devices. As the size of batteries decreases, the amount of energy they store also shrinks dramatically. The batteries needed for tiny computers are significantly smaller than the conventional small batteries used to energize other devices such as pacemakers and cochlear implants—and, says Blaauw, their capacity may be a thousand times less.

One
possible solution is to find ways for devices to recharge themselves
frequently. For example, beams
of infrared light can remotely recharge sensors implanted in
laboratory mice. Scientists are also researching how to create electricity for
tiny computers using a technique known as thermoelectric
energy harvesting, though they have not yet found success at
such a small scale. For this latter method to work, there needs to be a
temperature difference between two surfaces of a device, but the new tiny
computers are so small that it’s hard to make any one part much warmer than any
other. Other methods still under investigation include harnessing
glucose molecules as a power source.

An
effective solution is simply to conserve the small amount of power that can be
stored on a tiny battery. Blaauw and his team have learned that they can drastically
reduce power usage by only waking the computers up periodically
to make calculations, then putting them to sleep again.

In
addition to maximizing the amount of time that tiny computers are asleep,
engineers can reduce power usage by cutting back on how much electricity the
computers draw while awake. Blaauw and his team were able to reduce the resting
power consumption of their computer to an infinitesimal 30
picowatts—300 trillionths of a watt—by modifying which transistors
they used; reducing the size of some of the circuits; and making some circuit
optimizations.

The small
size and reduced power draw of tiny computers means nothing, of course if the
data they gather can’t be properly communicated. This process, too, had to be
modified by Blaauw and his team to consume as little electricity as possible.
By turning on a radio antenna for transmission bursts lasting only a few
billionths of a second, the computers can make themselves known without too
much energy expenditure. “In order for a radio to be heard, it has to scream
pretty loudly,” Blaauw said. “What we’ve essentially done is instead of
screaming all the time, we just scream a short blip.”

If teams like Blaauw’s can overcome the technological obstacles, tiny computers could one day revolutionize more than just tumor detection. For example, CubeWorks, a company spun off from the University of Michigan’s Michigan Micro Mote (M3) initiative, has developed a system of networked micro-sensors that can be embedded into objects we use every day such as smart home systems, wind farms, and devices to monitor glucose levels, and then linked to the Internet of Things (IoT). Powered by the sun, these computers can gather information about the temperature and pressure of their environments, as well as take digital images and follow motion within a given area through Internet of Things tracking. One day, systems like these may transform how we interact with everything from smart buildings to smart cities.

Though we
still may not be able to launch submarines inside our bodies, millimeter-sized
computers will likely make it to market in the next decade—and begin to have a
major impact on the world.